Movement of heparins across rat gastric mucosa is dependent on molecular weight and pH.
OBJECTIVE
Movement of unfractionated (UFH) and low molecular weight heparins (LMWHs) through gastric mucosa was compared to determine effect of molecular weight on absorption.


METHODS
Rat gastric mucosa, mounted in an Ussing chamber, was bathed in oxygenated Kreb's buffer, containing mannitol on the mucosal (lumen) at pH 7.4 or 4, and glucose on the serosal side (circulation) at pH 7.4. Heparins (10 mg/ml) were added to the mucosal side. Potential difference (PD), resistance, and short circuit current (Isc), were determined. Buffers and tissues were extracted to measure heparin by gel electrophoresis.


RESULTS
PD increased on heparin addition and following a lag period, that was longer for UFH at pH 7.4 and LMWHs at pH 4.0, returned to baseline. Isc increased slightly for UFH at pH 4.0 but significantly for LMWHs at pH 7.4. More UFH or LMWHs were recovered from serosal buffers at pH 4.0 and pH 7.4 respectively. Results suggest UFH and LMWHs cross gastric mucosa faster, and active transport is involved, at pH 4.0 and pH 7.4, respectively.


CONCLUSIONS
Decreasing heparin size, increases movement through gastric mucosa at mucosal buffer pH 7.4 but not pH 4.0. The stomach environment may favor UFH absorption while the intestine environment favors LMWH absorption.
Moazed
Bita
B
Department of Veterinary Biomedical Sciences, Western College of Veterinary Medicine, University of Saskatchewan, 52 Campus Drive, Saskatoon, Saskatchewan, S7N 5B4, Canada.
Hiebert
Linda M
LM
D000042:Absorption; D000818:Animals; D000925:Anticoagulants / Q000737:chemistry* / Q000378:metabolism*; D002021:Buffers; D015194:Diffusion Chambers, Culture; D005753:Gastric Mucosa / Q000378:metabolism*; D006493:Heparin / Q000031:analogs & derivatives / Q000737:chemistry* / Q000378:metabolism*; D006495:Heparin, Low-Molecular-Weight / Q000737:chemistry / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D008970:Molecular Weight; D051381:Rats
D000925:Anticoagulants; D002021:Buffers; D006495:Heparin, Low-Molecular-Weight; C094240:reviparin; D006493:Heparin